The use of encryption to enhance the security of communications is well known. Encryption is commonly used by the military, government agencies, defense contractors, and others to facilitate secret communications. Many commercial systems also utilize encryption. For example, banks use encryption to perform wire transfers, to provide access to account information, and in other applications. Encryption is commonly used in Internet commerce to facilitate sales transactions.
Encryption is the process of transforming information, such as text, from its original form into an encrypted form. Typically, the original form of the information can be readily understood and used. For example, text in the original form can be read. However, the same information in encrypted form is only usable to those who can reverse the encryption process, i.e., decrypt the information.
Original or unencrypted text is commonly referred to as plaintext. Encrypted text is commonly referred to as cyphertext. An encryption algorithm is used to transform plaintext into cyphertext. Similarly, a decryption algorithm is used to transform cyphertext into plaintext. A key is required in order for the encryption algorithm to transform plaintext into cyphertext and in order for the decryption algorithm to transform cyphertext into plaintext.
Although contemporary encryption has proven generally useful for its intended purposes, contemporary encryption does possess limitations that affect its usefulness in some applications. For example, contemporary encryption is not well suited for use in applications where short message length is desirable, such as in low bandwidth applications and in environments that are subject to jamming.